1. Field of the Invention
This invention relates to shielded electrical connectors.
2. Description of the Prior Art
In the mutual connection between high frequency machines, it becomes necessary to eliminate the effect of an external noise in the connecting cable, etc. Generally, therefore, a shielded cable is employed as a connecting cable and, at the same time, the plug connector which is used for connection is provided with an electroconductive cover, where the external jacket of the shield for the cable is connected.
At the time when this connector has been inserted into the receptacle of a high frequency machine, along with the mutual connection among the contacts, the cover of the plug connector is electrically connected with an electroconductive cover of the receptacle, with a result that the outer cover of the shield may be grounded through the housing of the high frequency machine in the receptacle.
In the case of the conventional connector, however, the number of parts involved is relatively large, with a consequence that it is troublesome and relatively expensive to manufacture. In addition, the connecting operation becomes complicated and, moreover, the shielding effect is insufficient.
A prior art connector is shown in FIG. 1, and includes a connector A having an insulator 2 supporting contacts 1 having connection terminal elements 1a. Connector A is provided with electrically conductive covers 3 and 4 which may have flanges 3a and 4a that are integrally joined respectively in the screw insertion holes 3b, 4b (only holes 4b are visible). A flat and generally tubular shield cover B is used which has a cable withdrawal hole 5a at one end and with screw receptacles 5b at the other end. Shield cover B has an opening 5d surrounded by a flange 5c. A cable clamp C comprising first and second metal members 7 and 8 and a tightening screw 6 is fixed to cover B adjacent cable withdrawal hole 5a thereof by such means as soldering.
Accordingly, the total number of component parts of the prior design reaches as many as nine, with a result that the structure involved becomes complicated and that the price also rises accordingly.
In regard to the connection of the cables, moreover, one end of the cable 9 is inserted into the shield cover B through the metal clamp C and the cable withdrawal hole 5a and is pulled out of the opening 5d, followed by the connection of the base wires with the connection terminal elements 1a of the connector A.
Thereafter, the connector A is fixed to the opening part 5d of the shield cover B by means of a female screw hole 5b and installation screws 10 extending into receptacles 5b and the cable 9 which has been passed into the metal clamp C is finally tightened by tightening screws 6. After assembly, the shield outer cover 9a of the cable will have to be electrically connected with the shield cover B and, at the same time, it will have to be mechanically fixed.
Accordingly, the prior art construction is not only complicated but the connecting operation is also troublesome. Since the shield cover B is tubular, moreover, should it be forgotten to install shield cover B over the cable 9, it becomes necessary to release the connection between the connector and the cable which have already been connected, install the shield cover and again connect the connector.
Moreover, the metal clamp C is made so as to be able to clamp against cables having diameters which are within a certain range. The cable withdrawal hole 5a is also chosen in accordance with the same principle. As a result, if the diameter of the cable is small as compared with the size of the hole, tightening becomes dissatisfactory and, accordingly, there develops a possibility of grounding becoming dissatisfactory. Moreover, a leakage of electric waves takes place from the gap between the cable withdrawal hole 5a of the shield cover B and the cable 9. Because of this, there is a shortcoming in that the shielding effect becomes dissatisfactory.
It would be desirable to provide a connector which is small in size and low cost, which has a shielding effect and which eliminates various kinds of shortcomings experienced in a conventional connector as has been described above.